Head-mounted display apparatuses

ABSTRACT

A head-mounted display apparatus is disclosed. The head-mounted display apparatus includes an optical member having a front surface, a rear surface, and a plurality of side surfaces, a display unit adapted to emit a display image toward one of the side surfaces of the optical member, and a reflective structure disposed inside the optical member to reflect the display image emitted from the display unit and to allow the reflected display image to pass and propagate through the rear surface. The image reflected by the reflective structure and delivered to user&#39;s eyes is the same irrespective of the coverage of the user&#39;s field of view.

TECHNICAL FIELD

The present disclosure relates to head-mounted display apparatuses, andmore specifically to head-mounted display apparatuses that include anoptical structure accommodating a reflective structure without having aneed for a fixing mechanism, contributing to size and weight reduction,allow a user to view the same clear display image irrespective of acoverage of his/her field of view, and achieve virtual reality andaugmented reality.

BACKGROUND

In recent years, a great deal of research has been conducted onhead-mounted displays (HMDs). Eyewear display apparatuses operate insuch a manner that enlarged images are allowed to come into sight. Sucheyewear display apparatuses can offer two advantages: their structure issmall enough to be wearable on the eyes and extended screens can beprovided. Most conventional eyewear display apparatuses formicro-display applications are operated in such a manner that opticalsignals are reflected by a prism. One example of such eyewear displayapparatuses is disclosed in KR 10-2014-0053341 (published on May 7,2014). However, a volume and weight of a prism used in the eyeweardisplay apparatus remain problematic. The use of the prism has become anobstacle to a diversification of the design of the eyewear displayapparatus.

There has been an increasing demand for wearable devices, such asglasses and goggles, that can provide dynamic digital information withhigher image quality in various applications, such as augmented realitysystems. Nevertheless, conventional eyewear display apparatuses aloneare insufficient in providing various designs and dynamic informationwith high image quality. As such, there is still a need for enhancedtechnology and/or techniques for providing various designs and dynamicinformation with high image quality.

SUMMARY

In an aspect of the present technology, head-mounted display apparatusesare provided, which can be attached to glass parts of eye-wearabledevices, such as glasses or goggles, to diversify the design of theeye-wearable devices, making the eye-wearable devices compact in sizeand light in weight.

One aspect of the present technology provides a head-mounted displayapparatus including an optical member having a front surface, a rearsurface, and a plurality of side surfaces, a display unit adapted toemit a display image toward one of the side surfaces of the opticalmember, and a reflective structure disposed inside the optical member toreflect the display image emitted from the display unit and to allow thereflected display image to pass and propagate through the rear surfacewherein the image reflected by the reflective structure and delivered touser's eyes is the same irrespective of the coverage of the user's fieldof view.

According to one embodiment, the display image may include incidentlight between the display unit and the one of the side surfaces of theoptical member, refracted light propagating through the optical memberas a medium after being refracted by the one of the side surfaces of theoptical member, and output light exiting from the rear surface of theoptical member after being reflected by the reflective structure.

According to one embodiment, the optical member may include a siliconematerial.

According to one embodiment, the head-mounted display apparatus furtherincludes a glass part to which the optical member is attached and aframe to which the glass part is fixed.

According to one embodiment, the display unit may be mounted on theframe.

According to one embodiment, the reflective structure may include amicromirror arranged obliquely relative to a reference plane as avirtual plane extending from the front surface of the optical member tocover the reflective structure and the width (W) of an orthographicprojection of the micromirror and the height (H) of the micromirror aredetermined depending on an angle of incidence of the display image onthe micromirror, an angle of reflection of the display image from themicromirror, and a refractive index of the optical member.

According to one embodiment, the display unit may include a first lightemitting diode (LED) display panel including a plurality oftwo-dimensionally arrayed first micro-LEDs to emit a first wavelengthdisplay image, a second LED display panel including a plurality oftwo-dimensionally arrayed second micro-LEDs to emit a second wavelengthdisplay image, and a third LED display panel including a plurality oftwo-dimensionally arrayed third micro-LEDs to emit a third wavelengthdisplay image.

According to one embodiment, the display unit may further include asingle complementary metal oxide semiconductor (CMOS) backplane coupledto the first LED display panel, the second LED display panel, and thethird LED display panel and including a plurality of CMOS cellscorresponding to the first micro-LEDs, the second micro-LEDs, and thethird micro-LEDs to individually drive the micro-LEDs in groups.

According to one embodiment, the display unit may further include bumpselectrically connecting the micro-LEDs to the corresponding CMOS cellsin a state in which the micro-LEDs and the CMOS cells are arranged toface each other.

According to one embodiment, the micro-LEDs may be formed by growing afirst conductive semiconductor layer, an active layer, and a secondconductive semiconductor layer in this order on a substrate and etchingthe layers; each of the micro-LEDs has a vertical structure includingthe substrate, the first conductive semiconductor layer, the activelayer, and the second conductive semiconductor layer formed in thisorder; and the active layer and the second conductive semiconductorlayer are removed from the exposed portions of each of the first LEDdisplay panel, the second LED display panel, and the third LED displaypanel where none of the micro-LEDs are formed, such that the firstconductive semiconductor layer is exposed.

According to one embodiment, a first conductive metal layer may beformed over a portion of the first conductive semiconductor layer wherenone of the micro-LEDs of each of the first LED display panel, thesecond LED display panel, and the third LED display panel are formed.

A further aspect of the present technology provides a head-mounteddisplay apparatus including an optical member having a first surface anda second surface and formed with a cut-away portion having a verticalplane and an inclined plane, a display unit adapted to emit a displayimage, and a micromirror arranged on the inclined plane of the cut-awayportion formed in the optical member to reflect the display imageemitted from the display unit and to allow the reflected display imageto pass and propagate through the first surface wherein the width (W) ofan orthographic projection (whose reference plane is defined as avirtual plane extending from the second surface to cover the cut-awayportion) of the micromirror and the height (H) of the micromirror aredetermined depending on the angle of incidence of the display image onthe micromirror, the angle of reflection of the display image from themicromirror, and the refractive index of the optical member.

The head-mounted display apparatuses of the present technology may beattached to glass parts of eye-wearable devices, such as glasses orgoggles, to diversify the design of the eye-wearable devices, making theeye-wearable devices compact in size and light in weight, and canachieve virtual reality and augmented reality.

In addition, the head-mounted display apparatuses of the presenttechnology may allow a display image reflected by the micromirror tofall at a constant position on the user's retina irrespective of whetherthe user see a distant or close object. Therefore, the use of thehead-mounted display apparatuses according to the present technology canprevent the quality of a display image from deteriorating depending onthe coverage of the user's field of view, compared to the use ofconventional head-mounted display apparatuses.

Furthermore, the head-mounted display apparatuses of the presenttechnology may allow an image provided through the micromirror from thedisplay unit to fall on the retina, achieving multiple focusing.Therefore, the head-mounted display apparatuses of the present inventionmay be effective in relieving eye strain compared to conventionalhead-mounted display apparatuses.

Moreover, the head-mounted display apparatuses of the present technologymay be attached to glass parts of eye-wearable devices, such as glassesor goggles, without having a need to modify the structure of the glassparts. Therefore, the head-mounted display apparatuses of the presenttechnology are efficient in terms of cost and management.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a view for explaining the pin hole effect associated with ahead-mounted display apparatus according to one embodiment of thepresent invention;

FIG. 2 is a view for explaining a head-mounted display apparatusaccording to one embodiment of the present invention;

FIG. 3 explains the propagation of a display image from a display unit20 to a user's eye through an optical member 10 and a pin hole 12 in thehead-mounted display apparatus of FIG. 2, as viewed from (a) F5 and (b)F2;

FIG. 4 is a view for explaining an embodiment of the head-mounteddisplay apparatus of FIG. 2;

FIG. 5 illustrates embodiments of the head-mounted display apparatus ofFIG. 2 applied to goggles;

FIG. 6 illustrates an exemplary procedure for manufacturing the opticalmember 10 of the head-mounted display apparatus of FIG. 2 in which afirst part 10 a having a concave surface F14 and a second part 10 bhaving a convex surface F24 are separately prepared and the two partsare arranged such that the concave surface F14 is in face-to-facecontact with the convex surface F24;

FIG. 7 illustrates exemplary pin holes 12 and reflective members 14 ofthe head-mounted display apparatus of FIG. 2: each of (a) and (b)illustrates a pin hole penetrating from a front surface of the opticalmember to a rear surface thereof, each of (c) and (d) illustrates a pinhole extending to a middle portion of the optical member, each of (a)and (c) illustrates a planar reflective member, and each of (b) and (d)illustrates a concave reflective member;

FIG. 8 illustrates various exemplary arrangements of the display unit 20in the head-mounted display apparatus of FIG. 2, (a) on the right, (b)on the left, (c) below, and (d) above the optical member;

FIG. 9 illustrates a head-mounted display apparatus according to afurther embodiment of the present invention;

FIG. 10 illustrates the structure of a cut-away portion formed in anoptical member of the head-mounted display apparatus of FIG. 9;

FIG. 11 schematically explains the propagation of a display image beforereaching a user's eye;

FIG. 12 is a view for explaining the inclination factors of amicromirror;

FIG. 13 illustrates a head-mounted display apparatus according toanother embodiment of the present invention;

FIG. 14 illustrates a head-mounted display apparatus according toanother embodiment of the present invention;

FIG. 15 illustrates a head-mounted display apparatus according toanother embodiment of the present invention;

FIG. 16 is a detailed view illustrating one example of a display unit 20of a head-mounted display apparatus according to the present invention;

FIG. 17 illustrates (a) first, (b) second, and (c) third LED displaypanels of the display unit 20 illustrated in FIG. 16; and

FIG. 18 illustrates a method for constructing the display unit 20 bycoupling the first, second, and third LED display panels illustrated inFIG. 17 to a CMOS panel.

DETAILED DESCRIPTION

Preferred embodiments of the present invention will now be describedwith reference to the accompanying drawings. It should be noted that thedrawings and embodiments described with reference to the drawings aresimplified and illustrated such that those skilled in the art canreadily understand the present invention.

FIG. 1 is a view for explaining the pin hole effect applied to ahead-mounted display apparatus according to one embodiment of thepresent invention. As illustrated, for a short-sighted user, an image isfocused in front of the retina. Images of {circle around (1)}, {circlearound (2)}, and {circle around (3)} marked with arrows overlap and areblurred on the retina. However, as illustrated in FIG. 1, when theportions {circle around (1)} and {circle around (3)} of light areblocked before entering the lens of the eye and only the portion {circlearound (2)} is allowed to enter the lens of the eye through a pin hole,a clear image is focused on the retina. This result arises from theeffect of the pin hole on the image.

One embodiment of the present invention based on the pin hole effectwill be explained with reference to FIGS. 2 to 8. As illustrated inthese figures, a display image is emitted from a display unit 20, isreflected by a reflective structure disposed in an optical member 10,passes through a rear surface of the optical member 10, and reaches auser's eye. In this embodiment, the reflective structure includes areflective member 14 and a pin hole 12 accommodating the reflectivemember 14.

In FIGS. 2, 3, 6, 7, and 8, the display image includes incident lightL1, refracted light L2, and output light L3, each of which isrepresented by a single straight line to assist in understanding. Inactuality, the straight line is meant to include display images (i.e.image lights) emitted from a plurality of micro-LEDs of the display unit20.

Specifically, FIG. 2 is a view for explaining a head-mounted displayapparatus according to one embodiment of the present invention, FIG. 3explains the propagation of a display image from a display unit 20 to auser's eye through an optical member 10 and a pin hole 12 in thehead-mounted display apparatus of FIG. 2, as viewed from (a) F5 and (b)F2, FIG. 4 is a view for explaining an embodiment of the head-mounteddisplay apparatus of FIG. 2, FIG. 5 illustrates embodiments of thehead-mounted display apparatus of FIG. 2 applied to goggles, FIG. 6illustrates an exemplary procedure for manufacturing the optical member10 of the head-mounted display apparatus of FIG. 2 in which a first part10 a having a concave surface F14 and a second part 10 b having a convexsurface F24 are separately prepared and the two parts are arranged suchthat the concave surface F14 is in face-to-face contact with the convexsurface F24, FIG. 7 illustrates exemplary pin holes 12 and reflectivemembers 14 of the head-mounted display apparatus of FIG. 2: each of (a)and (b) illustrates a pin hole penetrating from a front surface of theoptical member to a rear surface thereof, each of (c) and (d)illustrates a pin hole extending to a middle portion of the opticalmember, each of (a) and (c) illustrates a planar reflective member, andeach of (b) and (d) illustrates a concave reflective member, and FIG. 8illustrates various exemplary arrangements of the display unit 20 in thehead-mounted display apparatus of FIG. 2, (a) on the right, (b) on theleft, (c) below, and (d) above the optical member.

Referring first to FIG. 2, the optical member 10 has a front surface F1,a rear surface F2, and a plurality of side surfaces F3, F4, F5, and F6.A pin hole 12 is formed in the optical member 10. The pin hole 12penetrates from the rear surface F2 to the front surface F1. Assumingthat a user wears the head-mounted display apparatus on his/her eye 1,the front surface F1 refers to the surface of the optical member 10 thatis distant from the eye 1, that is, the surface of the optical member 10that is opposite to the eye 1, and the rear surface F2 refers to thesurface of the optical member 10 of the optical member 10 that is closeto the eye 1, that is, the surface of the optical member 10 that facesthe eye 1. Examples of materials for the optical member 10 include, butare not limited to, glass, polycarbonate, and acrylic resins.

The pin hole 12 is circular in cross section and is typically from 0.1mm to 2 mm in diameter. The pin hole 12 may extend to a middle portionof the optical member 10 or may penetrate from the rear surface F2 ofthe optical member 10 to the front surface thereof. FIG. 2 illustratesthe pin hole 12 extending between the front surface F1 and the rearsurface F2 of the optical member 10. The relationships between the pinhole 12 and the reflective member 14 of the optical member 10 will beexplained below with reference to FIG. 7.

The reflective member 14 is located in the pin hole 12 to reflect adisplay image. The display image reflected by the reflective member 14passes through the pin hole 12, exits through the rear surface F2 of theoptical member 10, and reaches the eye 1.

With reference to FIG. 7, an explanation will be given of thecross-section and location of the reflective member 14 and therelationship between the reflective member 14 and the pin hole 12. InFIG. 7, (a) illustrates that the pin hole 12 penetrates from the rearsurface F2 of the optical member 10 to the front surface F1 thereof andthe reflective member 14 is planar, (b) illustrates that the pin hole 12penetrates from the rear surface F2 of the optical member 10 to thefront surface F1 thereof and the reflective member 14 and the reflectivemember 14 is in the shape of a concave lens, (c) illustrates that thepin hole 12 extends to a middle portion of the optical member 10 and thereflective member 14 is planar, and (d) illustrates that the pin hole 12extends to a middle portion of the optical member 10 and the reflectivemember 14 is in the shape of a concave lens. The reflective member 14 isnot limited to the shapes illustrated in (a) to (d) of FIG. 7 and may bemodified into any other shape that is advantageous for viewinghigh-quality images with the eye. As illustrated in (c) and (d) of FIG.7, when the pin hole 12 extends to a middle portion of the opticalmember 10, the reflective member 14 is located in the middle portion ofthe optical member 10, that is, at the point where the pin hole 12begins. Alternatively, when the pin hole 12 penetrates from the rearsurface F2 of the optical member 10 to the front surface F1 thereof, asillustrated in (a) and (b) of FIG. 7, the reflective member 14 islocated at a middle point of the pin hole 12 in the middle portion ofthe optical member 10.

The display unit 20 is an element through which a display image isoutput toward the optical member 10. The display unit 20 includes aplurality of micro-LEDs.

The display unit 20 is arranged opposite to one of the side surfaces F3,F4, F5, and F6 of the optical member 10 to output a display image towardthe optical member 10. The display image emitted from the plurality ofmicro-LEDs of the display unit 20 propagates through the optical member10 as a medium, is reflected by the reflective member 14, passes throughthe pin hole 12, exits from the rear surface F2, and reaches the eye 1.Exemplary embodiments of the display unit 20 will be explained in detailwith reference to the corresponding drawings.

A display image emitted from the display unit 20 is divided intoincident light L1 between the display unit 20 and the side surface F3,refracted light L2 propagating through the optical member 10 as a mediumafter being refracted by the side surface F3, and output light L3propagating through the pin hole 12 and exiting from the rear surface F2of the optical member 10 after being reflected by the reflective member14, as illustrated in FIGS. 2 and 3. As illustrated in an enlarged viewof portion “A” of FIG. 3, the refracted light L2 propagating through theoptical member 10 as a medium is reflected by the reflective member 14located in the pin hole 12 and the output light L3 passes through thepin hole 12 and reaches the eye 1 after being reflected by thereflective member 14.

Thus, the head-mounted display apparatus of the present inventionenables the delivery of the same quality of images to the user's eyethrough the pin hole irrespective of the coverage of the user's field ofview, and as a result, a high-quality display image is always focused onthe user's optic nerve. Therefore, the use of the head-mounted displayapparatus according to the present invention can prevent a display imagefrom being blurred depending on the coverage of the user's field ofview, compared to the use of conventional head-mounted displayapparatuses.

As illustrated in FIG. 4, the head-mounted display apparatus of thepresent invention can be fabricated by coupling the display unit 20 to aframe 50. Further, the head-mounted display apparatus of the presentinvention may be applied to wearable glasses or goggles. Thehead-mounted display apparatus of the present invention may be providedin pair, as illustrated in (a) of FIG. 5. Alternatively, thehead-mounted display apparatus of the present invention may be mountedin only one of the glass or goggle lenses, as illustrated in (b) of FIG.5.

Various methods may be used to manufacture the reflective structure ofthe head-mounted display apparatus in which the pin hole 12 is formed inthe optical member 10 and the reflective member 14 is arranged in thepin hole 12. FIG. 6 illustrates an exemplary method for manufacturingthe reflective structure. Specifically, the optical member 10 ismanufactured by separately preparing a first part 10 a having a concavesurface F14 and a second part having a convex surface F24 and arrangingthe two parts such that the concave surface F14 is in face-to-facecontact with the convex surface F24. In this case, surface processingneeds to be done such that the concave surface F14 comes intoface-to-face contact with the convex surface F24 over the largestpossible area. The pin hole 12 is formed at the interface where theconcave surface F14 is in face-to-face contact with the convex surfaceF24 and the reflective member 14 is arranged in the pin hole 12.

As illustrated in FIG. 8, the display unit 20 may be arranged (a) on theright side of the optical member 10, (b) on the left side of the opticalmember 10, (c) below the optical member 10 or (d) above the opticalmember 10.

FIGS. 9 to 18 illustrate head-mounted display apparatuses according toother embodiments of the present invention. Each of the head-mounteddisplay apparatuses includes an optical member 10 and a reflectivestructure disposed in the optical member 10. The reflective structureincludes a cut-away portion 12 and a micromirror 30 arranged on a slopeof the cut-away portion 12.

Also in FIGS. 9 to 18, a display image includes incident light L1, L11,and L12, refracted light L2, L21, and L22, reflected light L3, L31, andL32, and output light L4, L41, and L42, each of which is represented bya single straight line to assist in understanding. In actuality, thestraight line is meant to include display images (i.e. image lights)emitted from a plurality of micro-LEDs of the display unit 20.

Referring first to FIG. 9, the optical member 10 has a first surface F1and a second surface F2. Assuming that a user wears the head-mounteddisplay apparatus on his/her eye 1, the first surface F1 is the rearsurface of the optical member that faces the eye 1 and the secondsurface F2 is the front surface of the optical member that is oppositeto the eye 1. Examples of materials for the optical member 10 include,but are not limited to, silicone, glass, polycarbonate, and acrylicresins. The cut-away portion 12 of the optical member 10 is formed atthe second surface F2 and the micromirror 30 is arranged obliquely inthe cut-away portion 12. The display unit 20 is an element through whicha display image L1 is output toward the micromirror 30. The micromirror30 is an element that reflects a display image emitted from the displayunit 20. The reflected display image passes through the first surfaceF1, reaches the eye 1, and is focused on the retina. The micromirror 30is planar and its location may vary depending on the locations of theuser's both eyes, the distance between the user's eyes, and the size ofthe user's face.

Referring to FIGS. 9 to 13, the cut-away portion 12 of the opticalmember 10 has a vertical plane S1 and an inclined plane S2. The verticalplane S1 is formed by vertically cutting out a portion of the opticalmember 10 and extends from the second surface F2 to the lowest portionof the inclined plane S2. The height of the vertical plane S1 isrepresented by “H”. The inclined plane S2 is the bottom surface of thecut-away portion 12 on which the micromirror 30 is disposed. Asillustrated, the cross-section of the cut-away portion 12 takes theshape of a right triangle. The inclined plane S2 corresponds to thehypotenuse of the right triangle and the vertical plane S1 correspondsto one of the two sides meeting at a right angle. The micromirror 30 isformed on the inclined plane S2. When a reference plane is defined as avirtual plane extending from the second surface F2 to cover the cut-awayportion 12, the cross-section of an orthographic projection of themicromirror relative to the virtual plane corresponds to the other sideforming a right angle with the vertical plane and is represented by thewidth (W) of the orthographic projection of the micromirror. The heightof the micromirror 30 can be considered the height (H) of the verticalplane S1 because the micromirror 30 is disposed on the inclined planeS2.

The slope of the inclined plane S2 or the slope of the micromirror 30 isrepresented by θ₁, which can determine the height (H) of the verticalplane S1 and the width (W) of the orthographic projection of themicromirror. In order for a display image emitted from the display unit20 to reach the eye 1 through the optical member 10 and the micromirror30, the slope (θ₁) of the micromirror 30, that is to say, the height (H)of the vertical plane S1 and the width (W) of the orthographicprojection of the micromirror 20, should be determined depending on theangles of incidence (θ₀₃ and θ₀₅in FIG. 12) of the display image L2incident on the micromirror 30, the angles of reflection (θ₂ and θ₄ inFIG. 12) of the display image L3 from the micromirror 30, and therefractive index of the optical member 10.

As illustrated in FIG. 9, the cut-away portion 12 of the optical member10 is formed at the second surface F2 and the micromirror 30 is disposedon the inclined plane S2 of the cut-away portion 12. Alternatively, acut-away portion 12′ may be formed at a first surface F1′, asillustrated in FIG. 13. Also in this case, a micromirror 30′ may bearranged obliquely in the cut-away portion 12′. In order not to impedethe propagation of a display image (i.e. incident light L1′) from adisplay unit 20′ toward the micromirror 30′, it is preferred that aninclined portion 13′ of the cut-away portion 12′ on which themicromirror 30′ is not disposed has a larger angle than the angle ofincidence of the incident light L1′.

The display unit 20 is an element through which a display image isoutput toward the optical member 10. The display unit 20 includes aplurality of micro-LEDs. The display unit 20 is located to face thefirst surface F1 to output a display image toward the optical member 10.The display image emitted from the plurality of micro-LEDs of thedisplay unit 20 is refracted by the first surface F1, reflected by themicromirror 30, again refracted by the first surface F1, and reaches theeye 1, as illustrated in FIGS. 9 and 11.

With reference to FIGS. 9 to 12, a detailed explanation will be given ofthe propagation of a display image emitted from the display unit. Adisplay image emitted from the display unit 20 can be divided intoincident light L1 (L11 and L12 in FIG. 12) propagating between thedisplay unit 20 and the optical member 10, refracted light L2 (L21 andL22 in FIG. 12) refracted by the first surface F1 of the optical member10 as a medium and propagating through the optical member 10 as a mediumbefore being reflected by the micromirror 30, reflected light L3 (L31and L32 in FIG. 12) reflected by the micromirror 30 and propagatingthrough the optical member 10 to reach the first surface F1, and outputlight L4 (L41 and L42 in FIG. 12) exiting from the first surface F1.Finally, the output light L4 reaches the eye 1. The same output light L4(that is, the output display image) is delivered to the eye irrespectiveof the coverage of the user's field of view. Thus, a high-qualitydisplay image is always focused on the user's retina. Therefore, the useof the head-mounted display apparatus according to the present inventioncan prevent a display image from being blurred depending on the coverageof the user's field of view, compared to the use of conventionalhead-mounted display apparatuses.

FIG. 12 illustrates the propagation of a display image from the displayunit 20 to the eye 1 through the optical member 10 and the micromirror30. As illustrated in FIG. 12, some fundamental factors should be takeninto consideration when the optical member 10 and the micromirror 30 aremanufactured. Specifically, the refractive index of the optical member10 should be considered because a display image enters the opticalmember 10 through the first surface F1 and leaves the optical member 10before reaching the eye. Further, the angles of incidence (θ₀₃ and θ₀₅)of the display image on the micromirror 30 are equal to the angles ofreflection (θ₀₂ and θ₀₄) of the display image from the micromirror 30,respectively. Therefore, taking into consideration these factors, theangle of inclination (θ₀₁) of the micromirror 30, the height (H) of thevertical plane S1, and the width (W) of the orthographic projection ofthe micromirror 30 shall be determined.

FIG. 14 illustrates a head-mounted display apparatus according toanother embodiment of the present invention. As illustrated in FIG. 14,optical members 10 a and 10 b are attached to glass parts 40 a and 40 b,respectively. Specifically, first surfaces F1 and F1′ of the opticalmembers 10 a and 10 b may be attached to the glass parts 40 a and 40 b,respectively. In this case, the glass parts 40 a and 40 b are thesurfaces of glass lenses that are opposite to user's both eyes.Alternatively, second surfaces F2 and F2′ of the optical members 10 aand 10 b may be attached to the glass parts 40 a and 40 b, respectively.In this case, the glass parts 40 a and 40 b are the surfaces of glasslenses that face user's both eyes.

Referring to FIG. 14, the head-mounted display apparatus employsmicromirrors and further includes frames 50 a and 50 b in addition tothe glass parts 40 a and 40 b. The optical members 10 a and 10 b areattached to the glass parts 40 a and 40 b, respectively. The frames 50 aand 50 b fix the glass parts 40 a and 40 b, respectively. Particularly,the frames 50 a and 50 b are elements that allow a user to hang thehead-mounted display apparatus on his/her both ears. Display units 20 aand 20 b are attached to appropriate positions of the frames 50 a and 50b, respectively. The optical members 10 a and 10 b are preferably madeof a silicone material. The tackiness of the silicone materialfacilitates the attachment of the optical members 10 a and 10 b to theglass parts 40 a and 40 b, respectively. Any transparent material may beused for the optical members 10 a and 10 b so long as it can bemaintained attached to the glass parts. The micromirrors are indicatedby reference numerals 30 a and 30 b.

FIG. 15 illustrates a head-mounted display apparatus employingmicromirrors according to another embodiment of the present invention.As illustrated in FIG. 15, optical members 10 a and 10 b aremanufactured in the form of glass lenses as glass parts. Also in thiscase, display units 20 a and 20 b are mounted at appropriate positionsof frames 50 a and 50 b, respectively.

When the embodiment of FIG. 14 is compared with that of FIG. 15, thehead-mounted display apparatus of FIG. 14 can be fabricated at a reducedcost because it uses general glasses including glass parts and frameswithout further modification, unlike the head-mounted display apparatusof FIG. 15. Another advantage of the head-mounted display apparatus ofFIG. 14 is that the micromirrors can be replaced with normal ones whendamaged, contributing to a reduction in maintenance cost.

FIG. 16 is a detailed view illustrating one example of a display unit 20of a head-mounted display apparatus according to the present invention,FIG. 17 illustrates (a) a first LED display panel, (b) a second LEDdisplay panel, and (c) a third LED display panel of the display unit 20illustrated in FIG. 16, and FIG. 18 illustrates a method forconstructing the display unit 20 by coupling the first, second, andthird LED display panels illustrated in FIG. 16 to a CMOS panel.

Referring first to FIG. 16, the display unit 20 includes first, second,and third LED display panels 1100, 1200, and 1300, which include aplurality of two-dimensionally arrayed micro-LEDs 130 a, 130 b, and 130c, respectively.

The first, second, and third display panels 1100, 1200, and 1300 emitdisplay images of different wavelength bands. More specifically, thefirst LED display panel 1100 is designed to emit red display images, thesecond LED display panel 1200 is designed to emit green display images,and the third LED display panel 1300 is designed to emit blue displayimages. The display unit 20 includes a single CMOS backplane 2000adapted to individually drive the micro-LEDs 130 a, 130 b, and 130 c ofthe first LED display panel 1100, the second LED display panel 1200, andthe third LED display panel 1300 to achieve full color. The single CMOSbackplane 2000 includes a plurality of CMOS cells 230 corresponding tothe micro-LEDs 130 a, 130 b, and 130 c of the first, second, and thirdLED display panels 1100, 1200, and 1300. The CMOS backplane 2000 hasCMOS cell areas 2100, 2200, and 2300 in which the first, second, andthird LED display panels 1100, 1200, and 1300 are arranged,respectively. The first, second, and third LED display panels 1100,1200, and 1300 are flip-chip bonded to the CMOS cell areas 2100, 2200,and 2300, respectively. The CMOS cells 230 are electrically connected tothe LED cell 130 a, 130 b, and 130 c by flip-chip bonding of the LEDdisplay panels 1100, 1200, and 1300 to the single CMOS backplane 2000.For this electrical connection, the plurality of CMOS cells 230corresponding to the plurality of micro-LEDs of the LED display panels1100, 1200, and 1300 are formed in the CMOS cell areas 2100, 2200, and2300, respectively. The CMOS cells 230 are electrically connected to themicro-LEDs 130 a, 130 b, and 130 c through bumps 300.

A common cell 240 is formed in each of the CMOS cell areas 2100, 2200,and 2300 on the single CMOS backplane 2000. The common cells 240 areelectrically connected to first conductive metal layers of the LEDdisplay panels 1100, 1200, and 1300 through common bumps 340.

In the current state of the art, it is difficult to form structuresemitting red, green, and blue display images on a single substrate inthe construction of a display unit. In the present invention, theplurality of independently constructed LED display panels emitting red,green, and blue lights of different wavelength bands are flip-chipbonded to the single CMOS backplane 2000.

The display unit 20 is driven in response to control signals from adrive IC. The control signals from the drive IC are transmitted to themicro-LEDs 130 a, 130 b, and 130 c by the CMOS cells 230 (i.e. CMOSintegrated circuits) formed in the CMOS backplane 2000. The controlsignals from the drive IC may be analog or digital signals. The digitalsignals may also be pulse width modulation (PWM) signals.

The first, second, and third LED display panels of the display unit 20illustrated in FIG. 16 are illustrated in (a), (b), and (c) FIG. 17,respectively. Referring first to (a), (b) and (c) of FIG. 17, the LEDdisplay panels 1100, 1200, and 1300 are formed by growing firstconductive semiconductor layers 132 a, 132 b, and 132 c, active layers134 a, 134 b, and 134 c, and second conductive semiconductor layers 136a, 136 b, and 136 c in this order on transparent substrates 110 a, 110b, and 110 c, respectively, followed by etching. The resultingmicro-LEDs 130 a, 130 b, and 130 c formed on the first, second, andthird LED display panels 1100, 1200, and 1300 have vertical structuresincluding the first conductive semiconductor layers 132 a, 132 b, and132 c, the active layers 134 a, 134 b, and 134 c, and the secondconductive semiconductor layers 136 a, 136 b, and 136 c on thetransparent substrates 110 a, 110 b, and 110 c, respectively.

The transparent substrates 110 a, 110 b, and 110 c are made of amaterial selected from sapphire, SiC, Si, glass, and ZnO. The firstconductive semiconductor layers 132 a, 132 b, and 132 c may be n-typesemiconductor layers and the second conductive semiconductor layers 136a, 136 b, and 136 c may be p-type semiconductor layers. The activelayers 134 a, 134 b, and 134 c are regions where electrons from thefirst conductive semiconductor layers 132 a, 132 b, and 132 c recombinewith holes from the second conductive semiconductor layer 136 a, 136 b,and 136 c when power is applied.

The second conductive semiconductor layers 136 a, 136 b, and 136 c andthe active layers 134 a, 134 b, and 134 c are removed from the etchedportions 120 a, 120 b, and 120 c of the first, second, and third LEDdisplay panels 1100, 1200, and 1300 where none of the micro-LEDs 130 a,130 b, and 130 c are formed, and as a result, the first conductivesemiconductor layers 132 a, 132 b, and 132 c are exposed in the etchedportions, respectively. The LED display panels 1100, 1200, and 1300include first conductive metal layers 140 a, 140 b, and 140 c formedover the portions 120 a, 120 b, and 120 c of the first conductivesemiconductor layers 132 a, 132 b, and 132 c where none of themicro-LEDs 130 a, 130 b, and 130 c are formed, respectively. The firstconductive metal layers 140 a, 140 b, and 140 c are spaced apart fromthe micro-LEDs 130 a, 130 b, and 130 c, respectively. The firstconductive metal layers 140 a, 140 b, and 140 c are formed withpredetermined widths along the peripheries of the LED display panels1100, 1200, and 1300 on the first conductive semiconductor layers 132 a,132 b, and 132 c, respectively. The first conductive metal layers 140 a,140 b, and 140 c have substantially the same heights as the micro-LEDs130 a, 130 b, and 130 c, respectively. The first conductive metal layers140 a, 140 b, and 140 c are electrically connected to the CMOS backplane2000 through the bumps 340. As a result, the first conductive metallayers 140 a, 140 b, and 140 c function as common electrodes of themicro-LEDs 130 a, 130 b, and 130 c, respectively.

The plurality of CMOS cells 230 of the CMOS backplane 2000 serve toindividually drive the micro-LEDs 130 a, 130 b, and 130 c. The CMOScells 230 are electrically connected to the corresponding micro-LEDs 130a, 130 b, and 130 c through bumps 300. The CMOS cells 230 are integratedcircuits for individually driving the corresponding micro-LEDs 130 a,130 b, and 130 c. The CMOS backplane 2000 may be, for example, an activematrix (AM) panel. Specifically, each of the CMOS cells 230 may be apixel driving circuit including two transistors and one capacitor. Whenthe first, second, and third LED display panels 1100, 1200, and 1300 areflip-chip bonded to the CMOS backplane 2000 through the bumps, each ofthe micro-LEDs may be arranged between a drain terminal and a commonground terminal of a transistor of the pixel driving circuit to form anequivalent circuit.

The CMOS backplane 2000 includes common cells 240 formed at positionscorresponding to the first conductive metal layers 140 a, 140 b, and 140c. The first conductive metal layers 140 a, 140 b, and 140 c areelectrically connected to the common cells 240 through the common bumps340.

As illustrated in FIG. 18, the CMOS backplane 2000 on which the CMOScells 230 are arranged faces the first, second, and third LED displaypanels 1100, 1200, and 1300. After the CMOS cells 230 are brought intocontact with the micro-LEDs 130 a, 130 b, and 130 c in a one-to-onerelationship, the bumps 300 and the common bumps 340 are melted byheating. As a result, the CMOS cells 230 are electrically connected tothe corresponding micro-LEDs 130 a, 130 b, and 130 c.

Although the head-mounted display apparatuses employing micromirrorsaccording to the present invention have been described herein withreference to their embodiments, this description is not intended tofully encompass all embodiments, variations, or adaptations of theexamples and/or equivalents of the invention described herein.Therefore, it will be apparent to those skilled in the art that thescope of the present invention is not limited to the embodimentsdescribed herein and is defined by the claims that follows.

What is claimed is:
 1. A head-mounted display apparatus comprising: anoptical member having a front surface, a rear surface, and a pluralityof side surfaces; a display unit adapted to emit a display image towardone of the side surfaces of the optical member; and a reflectivestructure disposed inside the optical member to reflect the displayimage emitted from the display unit and to allow the reflected displayimage to pass and propagate through the rear surface, wherein thereflective structure comprises a micromirror arranged obliquely relativeto a reference plane as a virtual plane extending from the front surfaceof the optical member to cover the reflective structure, and wherein awidth of an orthographic projection of the micromirror and a height ofthe micromirror are determined depending on an angle of incidence of thedisplay image on the micromirror, an angle of reflection of the displayimage from the micromirror, and a refractive index of the opticalmember.
 2. The head-mounted display apparatus according to claim 1,wherein the display image comprises: incident light between the displayunit and the one of the side surfaces of the optical member, refractedlight propagating through the optical member as a medium after beingrefracted by the one of the side surfaces of the optical member, andoutput light exiting from the rear surface of the optical member afterbeing reflected by the reflective structure.
 3. The head-mounted displayapparatus according to claim 1, wherein the optical member includes asilicone material.
 4. The head-mounted display apparatus according toclaim 1, further comprising a glass part to which the optical member isattached and a frame to which the glass part is fixed.
 5. Thehead-mounted display apparatus according to claim 4, wherein the displayunit is mounted on the frame.
 6. The head-mounted display apparatusaccording to claim 1, wherein the display unit comprises: a first lightemitting diode (LED) display panel comprising a plurality oftwo-dimensionally arrayed first micro-LEDs to emit a first wavelengthdisplay image, a second LED display panel comprising a plurality oftwo-dimensionally arrayed second micro-LEDs to emit a second wavelengthdisplay image, and a third LED display panel comprising a plurality oftwo-dimensionally arrayed third micro-LEDs to emit a third wavelengthdisplay image.
 7. The head-mounted display apparatus according to claim6, wherein the display unit further comprises: a single complementarymetal oxide semiconductor (CMOS) backplane coupled to the first LEDdisplay panel, the second LED display panel, and the third LED displaypanel, the single CMOS backplane comprising a plurality of CMOS cellscorresponding to the first micro-LEDs, the second micro-LEDs, and thethird micro-LEDs to individually drive the micro-LEDs in groups.
 8. Thehead-mounted display apparatus according to claim 7, wherein the displayunit further comprises bumps electrically connecting the micro-LEDs tothe corresponding CMOS cells in a state in which the micro-LEDs and theCMOS cells are arranged to face each other.
 9. The head-mounted displayapparatus according to claim 8, wherein: the micro-LEDs are formed bygrowing a first conductive semiconductor layer, an active layer, and asecond conductive semiconductor layer in this order on a substrate andetching the layers; each of the micro-LEDs has a vertical structurecomprising the substrate, the first conductive semiconductor layer, theactive layer, and the second conductive semiconductor layer formed inthis order; and the active layer and the second conductive semiconductorlayer are removed from exposed portions of each of the first LED displaypanel, the second LED display panel, and the third LED display panelwhere none of the micro-LEDs are formed, such that the first conductivesemiconductor layer is exposed.
 10. The head-mounted display apparatusaccording to claim 9, wherein a first conductive metal layer is formedover a portion of the first conductive semiconductor layer where none ofthe micro-LEDs of each of the first LED display panel, the second LEDdisplay panel, and the third LED display panel are formed.
 11. Ahead-mounted display apparatus comprising: an optical member having afirst surface and a second surface and formed with a cut-away portionhaving a vertical plane and an inclined plane; a display unit adapted toemit a display image; and a micromirror arranged on the inclined planeof the cut-away portion formed in the optical member to reflect thedisplay image emitted from the display unit and to allow the reflecteddisplay image to pass and propagate through the first surface, wherein awidth of an orthographic projection of the micromirror, a referenceplane of the orthographic projection defined as a virtual planeextending from the second surface to cover the cut-away portion, and aheight of the micromirror are determined based on an angle of incidenceof the display image on the micromirror, an angle of reflection of thedisplay image from the micromirror, and a refractive index of theoptical member.
 12. The head-mounted display apparatus according toclaim 11, wherein the display image comprises: incident light betweenthe display unit and the one of the side surfaces of the optical member,refracted light propagating through the optical member as a medium afterbeing refracted by the one of the side surfaces of the optical member,and output light exiting from the rear surface of the optical memberafter being reflected by the reflective structure.
 13. The head-mounteddisplay apparatus according to claim 11, wherein the optical membercomprises a silicone material.
 14. The head-mounted display apparatusaccording to claim 11, further comprising a glass part to which theoptical member is attached and a frame to which the glass part is fixed.15. The head-mounted display apparatus according to claim 11, whereinthe display unit comprises: a first light emitting diode (LED) displaypanel comprising a plurality of two-dimensionally arrayed firstmicro-LEDs to emit a first wavelength display image; a second LEDdisplay panel comprising a plurality of two-dimensionally arrayed secondmicro-LEDs to emit a second wavelength display image; and a third LEDdisplay panel comprising a plurality of two-dimensionally arrayed thirdmicro-LEDs to emit a third wavelength display image.
 16. A head-mounteddisplay apparatus comprising: an optical member having a front surface,a rear surface, and a plurality of side surfaces; a display unit adaptedto emit a display image toward one of the side surfaces of the opticalmember; and a reflective structure disposed inside the optical member toreflect the display image emitted from the display unit and to allow thereflected display image to pass and propagate through the rear surface,wherein the display unit comprises: a first light emitting diode (LED)display panel comprising a plurality of two-dimensionally arrayed firstmicro-LEDs to emit a first wavelength display image, a second LEDdisplay panel comprising a plurality of two-dimensionally arrayed secondmicro-LEDs to emit a second wavelength display image, and a third LEDdisplay panel comprising a plurality of two-dimensionally arrayed thirdmicro-LEDs to emit a third wavelength display image.
 17. Thehead-mounted display apparatus according to claim 16, wherein thedisplay image comprises: incident light between the display unit and theone of the side surfaces of the optical member, refracted lightpropagating through the optical member as a medium after being refractedby the one of the side surfaces of the optical member, and output lightexiting from the rear surface of the optical member after beingreflected by the reflective structure.
 18. The head-mounted displayapparatus according to claim 16, wherein the optical member comprises asilicone material.
 19. The head-mounted display apparatus according toclaim 16, further comprising a glass part to which the optical member isattached and a frame to which the glass part is fixed.